Resistance Random Access Memory, or “ReRAM,” is a non-volatile memory device employing reversible change in resistance in a thin film with application of electrical voltage bias across the film. Application of the electrical voltage bias in one manner can cause decrease in the resistance of the thin film, for example, by formation of filaments that function as leakage current paths or by increasing a crystallinity of the thin film. Application of a different type of electrical voltage bias can cause reversal of the resistance of the thin film to an original high-resistance state, such as by removal of the filaments from the thin film or by decreasing the crystallinity of the thin film.
Thus, data can be stored in a ReRAM cell by changing the resistance of the thin film, which can be a solid-state material. The thin film is referred to as a memory film or a read/write film. Examples of ReRAM devices are described in World Intellectual Property Organization (WIPO) Publication No. WO2007004843 A1 to Hong et al. and U.S. Patent Application Publication No. 2013/0043455 A1 to Bateman.
A barrier-modulated cell (BMC) resistive random access memory (ReRAM) device is a ReRAM in which the resistance of a resistive memory element is modulated by separation or recombination of oxygen vacancies and oxygen ions. When the oxygen ions combine with the oxygen vacancies, a zone with a low density of charge carriers is formed, thereby increasing the resistance of the resistive memory element. This operation is herein referred to as a “resetting” operation. When the oxygen ions are separated from the oxygen vacancies, a zone with a high density of charge carriers is formed, thereby decreasing the resistance of the resistive memory element. This operation is herein referred to as a “setting” operation.
A filament-modulated cell (FMC) resistive random access memory (ReRAM) device is a ReRAM in which the resistance of a resistive memory element is modulated by presence of absence of conductive filaments within a dielectric oxide material. A high voltage applied in the forward direction forms conductive filaments, and a high voltage applied in the reverse direction removes the conductive filaments.
A phase-change material (PCM) resistive random access memory (ReRAM) device is a ReRAM in which the resistance of a resistive memory element is modulated by change of its phase or crystalline state based on the application of a voltage. For example, resistive memory element material may comprise a chalcogenide phase change material.